fix import json

app/routes/main.py

@@ -1,6 +1,7 @@
 # app/routes/main.py
 import os
 import logging
+import json
 
 from flask import Blueprint, render_template, redirect, url_for, request, jsonify, send_from_directory, current_app
 from app.utils.helpers import load_configs, load_default_sounds